TABLE OF CONTENTS There are many organic and inorganic actives available for use in plasticised PVC and other plastics. The major actives are summarised next and are split into two categories according to whether they migrate readily or not.
Known widely by its trade name Vinyzene (Morton now part of Rohm and Haas) this is typically available in 2% or 5% concentration in plasticiser or PVC pellets, 10,10 oxybisphenoxarsine (OBPA; Figure 25) was initially registered in the United States in 1965. It is used at a dose rate of 0.6-5% based on the total weight of the formulation.
OBPA currently accounts for about half of the market for plastic biostabilisers worldwide but this level is slowly diminishing due to environmental and health concerns. These considerations are highlighted by the potential leaching of arsenic from plastic articles disposed of in landfillsites and it has been hypothesised that toxic trimethylarsenate can be released following fungal degradation by Scopulariopsis brevicaulis. This latter theory has perhaps erroneously been linked to cases of Sudden Infant Death Syndrome, along with a number of other possible contributory chemicals such as antimony flame-retardants, in PVC covered cot mattresses (a.18).
The levels of arsenic are however fairly low which is often sufficient to achieve the MIC against the majority of fungi and bacteria of 10 mg/l. Upsher & Roseblade (a.19) have reported in 1984 that long-term activity of OPBA exposed at a jungle site is limited due to its leachability.
